1. Field of the Invention
The present invention relates generally to a process for fluid recovery, and more particularly to a process in which filtration and purification take place after matters in a fluid are caused to exhibit different phases by cooling.
The process of the present invention may be applied to the purification of various fluids such as gas and liquid. More particularly, the process is adapted for use in the recycling, purification and recovery of refrigerant in a refrigeration system.
2. Description of the Related Art
As is well known to those skilled in refrigeration systems, refrigerant is being recycled and reused in a refrigeration system, and the used refrigerant is repeatedly recovered and reprocessed so as to enhance its purity and hence its heat exchange capacity, which helps to keep the refrigeration system in good conditions.
The process of recovering refrigerants generally falls into two main types: the compressive type and the non-compressive type. In the former, the compressor serves as a driving element to compress or transport the refrigerant. In the latter, by means of the differences in temperature and pressure generated by a refrigeration unit on the refrigerant located in at least two regions of the refrigeration system, the refrigerant is returned via the filter to the recovery equipment. For the process of recovering refrigerant using the compressor, the lubricant in the equipment that has good solubility in refrigerant may easily dissolve in the refrigerant and be carried away in it. The compressor may be damaged due to loss of lubricant. For refrigerant recovery systems not using compressors, the lubricant may be carried by the refrigerant into the cooling tank of the recovery equipment, thus contaminating the recovered refrigerant. Besides, the lubricant will stick to the cooling unit in the cooling tank so that the heat transfer efficiency of the cooling unit drops, damaging the system. In addition, during the process of recovery, since the amount of refrigerant in the refrigeration system will gradually decrease, space occupied by gaseous refrigerant will gradually increase so that pressure drops. Consequently, the differences in temperature and pressure between the refrigerant in the recovery equipment and the refrigerant in the refrigeration system are reduced. In other words, the rate of refrigerant recovery will continue to drop to further lower the recovery efficiency.
In the related art, there has been taught a refrigerant recovering and purging system utilizing heating and evaporation, and filtration equipment with windows for purifying the refrigerant. Such prior art systems are all directed to use of filtration apparatus and evaporation to achieve purification of refrigerant. In U.S. Pat. No. 5,379,607, which describes a refrigerant recovery and recycling system in which the refrigerant is separated by distillation. Said patent also-teaches use of waste heat produced by the compressor to distill liquid refrigerant from liquid contaminants.
Although heating and evaporation may substantially separate the two matters in the fluid, the separation is not complete. Take refrigerant-as an example. While water and refrigerant may readily dissolve in each other, and refrigerant very readily attracts water molecules, water is also the greatest contaminating source of refrigerant. There will be some water moisture left in the vaporized refrigerant when using prior evaporation techniques.